全文获取类型
收费全文 | 367篇 |
免费 | 33篇 |
专业分类
财政金融 | 2篇 |
工业经济 | 77篇 |
计划管理 | 60篇 |
经济学 | 44篇 |
综合类 | 16篇 |
运输经济 | 1篇 |
贸易经济 | 108篇 |
农业经济 | 50篇 |
经济概况 | 42篇 |
出版年
2024年 | 1篇 |
2022年 | 14篇 |
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 15篇 |
2015年 | 7篇 |
2014年 | 17篇 |
2013年 | 37篇 |
2012年 | 22篇 |
2011年 | 37篇 |
2010年 | 33篇 |
2009年 | 26篇 |
2008年 | 16篇 |
2007年 | 18篇 |
2006年 | 20篇 |
2005年 | 13篇 |
2004年 | 14篇 |
2003年 | 22篇 |
2002年 | 12篇 |
2001年 | 13篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1992年 | 2篇 |
排序方式: 共有400条查询结果,搜索用时 15 毫秒
151.
本研究分别以大豆油、棉籽油为煎炸油,在180℃条件下对3种新疆特色食品馓子、牛肉丸、夹沙进行油炸.研究大豆油、棉籽油在煎炸过程中废弃指标酸价和总极性组分的变化规律.结果表明,随着油炸时间的延长,酸价和总极性组分均呈逐渐上升趋势;根据GB 2716—2018规定的煎炸油废弃指标限定值(总极性组分≥27%,酸价≥5 mg KOH/g),大豆油油炸馓子、牛肉丸和夹沙过程中废弃时间分别为56~64 h、64~72 h和48~56 h,棉籽油油炸馓子、牛肉丸和夹沙过程中废弃时间均为48~56 h;大豆油的煎炸稳定性强于棉籽油,更适合应用于上述3种食品的油炸生产.本研究为新疆特色食品油炸过程中煎炸油品质及废弃点判别提供了理论依据. 相似文献
152.
153.
介绍了酸焦油的性质及危害,综述了酸焦油生产燃料油、橡胶添加剂、配煤炼焦、表面活性剂等处置利用方式。 相似文献
154.
氨基酸作为神经递质和神经调质,是中枢神经系统刺激神经组织中肽类、蛋白质和其他生物活性成分的基础物质。对可作为神经递质和神经调质的氨基酸种类进行了介绍,并综述了其在大脑中的特异性代谢,指出氨基酸在大脑中的代谢是中枢神经系统代谢机制的重要部分。 相似文献
155.
在水热条件下以配体草酸与Zn(NO3)2.6H2O为反应原料,得到了配合物草酸锌。通过X-射线单晶衍射对其结构进行表征,结果表明,晶体属于三斜晶系,空间群为C2/c。晶胞参数为:Z=1,a=11.690(6),b=5.416(3),c=9.725(4),α=90,β=126.40(2),γ=9.919(2)°,V=495.6(4)3;R1=0.1507。晶体结构分析表明每个锌离子与6个氧原子配位(ZnO6),形成了八面体构型,其中与锌离子配位的6个氧原子中,有4个氧原子来自2个草酸根配体,另2个氧原子来自配位水分子,邻近的金属离子通过草酸根连接成一维链状结构,链间通过氢键作用连接为三维网络结构。 相似文献
156.
《Journal of medical economics》2013,16(1):175-184
AbstractBackground:Bone metastases are common in patients with advanced breast cancer, and place patients at risk for skeletal-related events (SREs) including pathologic fracture, spinal cord compression, hypercalcemia of malignancy, and the need for radiotherapy and/or surgery to bone. These SREs are associated with reduced survival and quality-of-life. The nitrogen-containing bisphosphonates Zometa (zoledronic acid, ZOL) and Aredia (pamidronate disodium, PAM) reduce SRE risk in patients with bone metastases from breast cancer. This database analysis compared SRE and mortality rates in a real-life setting in women with breast cancer receiving ZOL and PAM, and assessed long-term ZOL benefit.Methods:A retrospective, claims-based analysis was conducted using commercial and Medicare Advantage data from >45 US managed-care plans. Eligible adult patients had diagnoses for breast cancer and bone metastasis between 01/01/01 and 12/31/06, continuous enrollment in the health plan, and no evidence of bone metastasis or intravenous bisphosphonate (IV-BP) use for 6 months before their first ZOL or PAM infusion. Patients were followed until disenrollment (including mortality) or end of the analysis period (12/31/07). Persistency was defined as absence of a >45-day gap between IV-BP treatments.Results:Of 8757 patients (mean age, 58.1 [SD 12.4] years), ~ 30% were treated with ZOL, 15% with PAM, and 55% with no IV-BP. Patients treated with ZOL had a moderately lower incidence of SREs (mean, 36.2 vs 40.0 SREs/100 person-years; p?=?0.0707) and significantly lower mortality (mean, 6.5 vs 11.2 deaths/100 person-years; p?<?0.001) compared with PAM-treated patients. Longer persistency with ZOL was associated with lower risk of fracture and all SREs (trend-test p?=?0.0076 and p?=?0.0200, respectively).Limitations:Interpretation of this claims-based analysis must be tempered by the inherent limitations of observational data, such as imbalances in patient populations and the potential for bias in treatment selection.Conclusions:This analysis suggests that fewer than half of breast cancer patients with bone metastases receive IV-BPs. Longer persistence with ZOL was associated with lower SRE risk, and ZOL-treated patients had longer survival and a non-significant trend toward fewer SREs compared with PAM. 相似文献
157.
《Journal of medical economics》2013,16(1):185-194
AbstractBackground:Patients with bone metastases secondary to genitourinary (GU) cancer are at risk for skeletal-related events (SREs), including bone pain requiring palliative radiotherapy, fractures or surgery to bone, spinal cord compression, and hypercalcemia of malignancy. These SREs can be debilitating and potentially life-limiting. This study examined treatment practices and the association of treatment patterns with Zometa (zoledronic acid, ZOL), an intravenous bisphosphonate (IV-BP), with SREs and fractures. (Zometa is a registered trademark of Novartis Pharmaceuticals Corporation, USA.)Methods:Retrospective analysis of commercial and Medicare Advantage enrollment and medical claims data was performed to evaluate IV-BP use and SRE patterns in adult patients with GU cancers. Criteria included diagnosis of ≥1 bone metastasis and prostate cancer (PC), renal cell carcinoma (RCC), or bladder cancer (BlC) between January 2001 and December 2006; continuous healthcare plan enrollment for ≥6 months before the index date; and no evidence of prior IV-BP use. Patients were followed until disenrollment from the healthcare plan or December 2007.Results:Of 6347 patients (PC, n?=?4976; RCC, n?=?941; BlC, n?=?430; mean [standard deviation] age: 68.9 [11.1] years), only ~23% received ZOL. The mean time between diagnosis of bone metastasis and ZOL initiation was ~108 days. Among patients with PC, fracture risk was significantly smaller for ZOL vs no IV-BP (incidence rate ratio?=?0.70; p?<?0.001), and 2-year survival was significantly longer for ZOL-treated vs no IV-BP patients (p?=?0.007). Patients with longer persistency on ZOL had a smaller fracture risk than patients with shorter persistency. Sub-set analyses were not performed for RCC and BIC because the proportion of patients treated was too low.Limitations:Interpretation of this claims-based analysis must be tempered by the inherent limitations of observational data, such as limited and accurate available information, and unavailable information including clinical or disease-specific parameters.Conclusions:Intravenous BP therapy is not always received in patients with bone metastases secondary to GU cancers, and, when used, there are typically long time periods before treatment initiation. Without IV-BPs, PC patients have significantly larger risks of fracture and death compared with ZOL-treated patients, and benefits appear to be larger with increasing persistency on ZOL. 相似文献
158.
我国每年报废上百万吨的废干电池,钛白工业也会产生大量的废硫酸,这不仅浪费了资源,还严重污染了环境。根据废干电池和钛白废硫酸的特点,本工艺研究用钛白废硫酸浸出废干电池,通过硫化、氧化加热、置换、水解、氟化等净化除杂后,采用共沉淀法制取锰锌铁氧体,产品初始磁导率达8000以上,杂质质量分数小于10-4。该工艺采取以废治废,废物中的主要成分不需相互分离即可制取高附加值的锰锌铁氧体,少量的杂质元素可通过净化脱除并进行处置。 相似文献
159.
在蔗糖业中开展生物炼制,利用生物质开发绿色平台小分子(如乙酰雨酸),是解决能源危机的重要途径,也符合蔗糖业规避风险和提高市场应变能力的要求。文章分析了蔗糖制备乙酰丙酸的原理和催化剂选择,并以几种固体无机酸催化为例说明,制备中可采用超声一微波协同技术提高生产效率,高效液相色谱法在分离提纯产品中能发挥较好作用。 相似文献
160.
针对兖矿国泰化工有限公司混合离子交换器(又名混床)运行恶化,造成混床周期制水量急剧下降,供脱盐水紧张,混床再生频繁,酸、碱耗高等问题,进行了原因分析并采取措施,使混床恢复运行正常,为企业创造了很好的经济效益. 相似文献